Building RESTful APIs with Flask

RESTful APIs are the backbone of modern web applications. Flask makes it easy to build robust APIs that follow REST principles.

What is REST?

REST (Representational State Transfer) is an architectural style for designing networked applications. RESTful APIs use HTTP methods to perform operations:

• GET: Retrieve data
• POST: Create new resources
• PUT: Update entire resources
• PATCH: Partially update resources
• DELETE: Remove resources

Setting Up Flask for APIs

Start by creating a Flask application:

from flask import Flask, jsonify, request
from flask.views import MethodView

app = Flask(__name__)

# Sample data store
books = [
    {'id': 1, 'title': 'Python Guide', 'author': 'John Doe'},
    {'id': 2, 'title': 'Flask Tutorial', 'author': 'Jane Smith'}
]

Creating REST Endpoints

GET - Retrieve All Resources

@app.route('/api/books', methods=['GET'])
def get_books():
    return jsonify({'books': books})

GET - Retrieve Single Resource

@app.route('/api/books/<int:book_id>', methods=['GET'])
def get_book(book_id):
    book = next((b for b in books if b['id'] == book_id), None)
    if not book:
        return jsonify({'error': 'Book not found'}), 404
    return jsonify(book)

POST - Create New Resource

@app.route('/api/books', methods=['POST'])
def create_book():
    data = request.get_json()
    new_book = {
        'id': len(books) + 1,
        'title': data['title'],
        'author': data['author']
    }
    books.append(new_book)
    return jsonify(new_book), 201

PUT - Update Resource

@app.route('/api/books/<int:book_id>', methods=['PUT'])
def update_book(book_id):
    book = next((b for b in books if b['id'] == book_id), None)
    if not book:
        return jsonify({'error': 'Book not found'}), 404

    data = request.get_json()
    book.update(data)
    return jsonify(book)

DELETE - Remove Resource

@app.route('/api/books/<int:book_id>', methods=['DELETE'])
def delete_book(book_id):
    global books
    books = [b for b in books if b['id'] != book_id]
    return jsonify({'message': 'Book deleted'}), 200

Error Handling

Implement proper error handling:

@app.errorhandler(404)
def not_found(error):
    return jsonify({'error': 'Resource not found'}), 404

@app.errorhandler(500)
def internal_error(error):
    return jsonify({'error': 'Internal server error'}), 500

Best Practices

1. Use proper HTTP status codes
2. Validate input data
3. Implement pagination for large datasets
4. Use API versioning (/api/v1/books)
5. Add authentication and authorization
6. Document your API (Swagger/OpenAPI)

Conclusion

Building RESTful APIs with Flask is straightforward. Follow REST principles, handle errors properly, and your APIs will be robust and maintainable.